1. Field of the Invention
The present invention relates to an airbag device for side collisions arranged in a seat of a vehicle. This side collision airbag device arranges an inflated airbag, when activated, between the interior wall and the passenger.
2. Description of the Related Art
In the side collision airbag device of the prior art, as disclosed in Unexamined Published Japanese Patent Application No. 9-315245, the airbag is folded and arranged on an upper side in the back portion of a seat.
This airbag takes, when inflated, a substantially rectangular shape. This airbag is mounted and fixed at a plurality of vertical portions on its rear edge side on a seat frame. Further, the airbag includes a lower chamber and an upper chamber. The lower chamber provides an upstream side portion for an inflating gas. The upper chamber is arranged over the lower chamber.
For assembling the airbag with the seat, moreover, the upper chamber side of the airbag is folded at first inward towards the lower chamber. Next, the airbag is folded in a rolling manner so as to bring the front edge sides of the upper and lower chambers toward the rear edge side. After this, the airbag is mounted and fixed on the seat frame and arranged in the back portion of the seat.
An inflator for inflating the airbag is arranged in the lower chamber of the airbag on the side of the rear edge.
In the side collision airbag device of the prior art, however, the process for folding the airbag is limited to only folding the upper chamber inside towards the lower chamber, and then to folding the front edge side of the airbag on the side of the rear edge. At the acting time of the inflator, therefore, the airbag is extended and inflated in a predetermined pattern in accordance with the output of the inflator. In this pattern, the airbag is protruded forward while eliminating the fold, and the upper chamber is protruded upward from the lower chamber.
For a predetermined time period after the action of the inflator and before the completion of inflation, more specifically, the extended and inflated shape of the airbag is fixed. In other words, an area capable of restricting the passenger with the airbag is fixed for a predetermined time period before the completion of inflation after the action of the inflator.
When the arranged position of the airbag, the output of the inflator, the size and shape of the back portion of the seat are changed, therefore, it becomes necessary to change the shape of the airbag, because the extended area of the airbag capable of restricting the passenger before the end of inflation is arranged at a predetermined position.